physics

Pelicans tuck their wings and free-fall straight down when diving for fish. Suppose a pelican starts its dive from a height of 15.0 m and cannot change its path once committed.

If it takes a fish 0.25 s to perform evasive action, at what minimum height must it spot the pelican to escape? Assume the fish is at the surface of the water.

  1. 👍
  2. 👎
  3. 👁
  1. The fish must spot the pelican when it is 0.25 s (or more) from hitting the water.

    The pelican takes
    t = sqrt(2H/g) = 1.75 s to hit the water if it starts its dive at H = 15 m.

    Its vertical drop 1.50 s after starting the dive is y = (1/2)g*(1.50)^2 = 11.03 m
    It is 15 - 11.03 = 4.97 m above the water surface at that time,

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics HELP ASAP PLEASE

    A hawk is flying horizontally at 10 m/s in a straight line 200m above the ground. A mouse it was carrying is released from its grasp. The hawk continues on its path at the same speed for two seconds before attempting to retrieve

  2. Statistics

    Suppose a basketball player is an excellent free throw shooter and makes 90% of his free throws (i.e., he has a 90% chance of making a single free throw). Assume that free throw shots are independent of one another. Suppose this

  3. physics

    A pelican flying along a horizontal path drops a fish from a height of 5.4m. The fish travels 8.0 m horizontally before it hits the water below. What was the pelican's speed?

  4. physics

    If the pelican was traveling at the same speed but was only 2.3 m above the water, how far would the fish travel horizontally before hitting the water below? Answer in units of m

  1. Physics

    A diver can reduce her moment of inertia by a factor of about 3.5 when changing from a straight position to a tuck position. If she makes two rotations in 1.5s when in the tuck position, what is her rotational speed (rot/s) when

  2. diffeq

    Suppose a species of fish in a particular lake has a population that is modeled by the logistic population model with growth rate k, carrying capacity N, and time t measured in years. Suppose the growth-rate parameter k=.3 and the

  3. Physics

    A pelican flying along a horizontal path drops a fish from a height of 3.3 m. The fish travels 8.2 m horizontally before it hits the water below. What was the pelican's initial speed? The acceleration of gravity is 9.81 m/s^.

  4. math

    Suppose you have $60 to buy shrimp and chicken wings for a party. Shrimp costs $10/lb and wings cost $6/lb. Write and graph a linear equation that could be used to determine the number of pounds of each food that can be purchased

  1. Physics

    Which statement reagarding the idealized model of motion called free fall is true? A. A freely falling object has a constant acceleration called the acceleration due to gravity. B. The idealized model of motion called free fall

  2. physics

    A small fish is dropped by a pelican that is rising steadily at 0.60 m/s. After 2.8 s, what is the velocity of the fish? The acceleration of gravity is 9.81 m/s2. How far below the pelican is the fish after the 2.8 s?

  3. Genetics

    In Drosophila melanogaster, the genes for purple eyes (pr) and curved wings (c) are on the same chromosome. The recombination frequency between pr and c is roughly 20%. Both the purple eyed and curly winged phenotypes are

  4. physics

    A bungee jumper falls for 1.3 seconds before the bungee cord begins to stretch. Until the jumper has bounced back up to this level, the bungee causes the jumper to have an acceleration upward of 4 m/s2. a. How fast is the jumper

You can view more similar questions or ask a new question.